1. Field of the Invention
This invention relates to a purification process of a polymerization solvent, and specifically to a process for purifying a polymerization solvent which is to be employed upon polymerization of an olefin in the presence of a Ziegler-Natta catalyst.
2. Description of the Prior Art
It is extremely important to purify a polymerization solvent prior to its use for the polymerization of an olefin in the presence of a Ziegler-Natta catalyst, because the Ziegler-Natta catalyst is deactivated by various poisonous components such as compounds with polar groups contained therein. For this reason, its purification is usually carried out under precisely-controlled operational conditions in a distillation column of an extremely sophisticated design. It is also practiced to use an adsorbent as needed, whereby polymerization-inhibiting components are adsorbed.
Although the above-mentioned distillation-dependent purification process may be a preferable process where such polymerization-inhibiting components can be specified and their contents remain constant, it may not be able to achieve desired purification if associated polymerization-inhibiting components cannot be specified or their contents vary.
On the other hand, the process making use of an adsorbent requires an extremely high cost for the processing because the adsorbent can generally adsorb extremely little compared with its own amount and when polymerization-inhibiting components are contained at high concentrations, this process cannot treat the polymerization solvent in any large volume. Moreover, another problem is involved in an actual practice of this process on an industrial scale, that is, it is difficult to analyze whether any polymerization-inhibiting components are mixed in a treated polymerization solvent. There is thus a standing desire for the development of a simple and economical purification process.